Climate and hydrologic fluctuations in the Pacific Northwest lead to large year-to-year variations in the strength of the Columbia River hydropower resource. We describe and present results from a seasonal hydrologic prediction system for the Columbia River basin that gives insight into the seasons-ahead behavior of this resource starting near the beginning of each water year. The forecast system is based on the real-time application of a state-of-the-science, macroscale hydrologic model coupled with ensemble climate forecasts. Estimates of initial land surface conditions, primarily in the form of snow water equivalent, are improved via the assimilation of snowpack observations, and forecast biases are reduced through statistical forecast calibration. The forecast system produces graphical forecast products designed to help water and energy managers understand the current state of the Columbia River basin, the climate outlook for the water year, and the implications of both for future streamflow.

The ability to identify renewable energy resources is of paramount importance in reducing fossil fuel dependency and addressing climate change. The Rapid Hydropower Assessment Model (RHAM) uses a Geographic Information System (GIS) to identify hydroelectric power opportunities. Using a Digital Elevation Model (DEM) and regional hydrologic data, RHAM calculates the amount of hydroelectric power available on all streams in a study area, screening out sites within parks and environmentally sensitive areas, and estimates project costs. RHAM can also assess the suitability of hydroelectric development in a given area, taking into account economic, environmental and social factors, and can assess storage hydro and clustered developments.

n 2007, RHAM was used to assess run-of-river hydroelectric potential for the Province of British Columbia, Canada, an area of approximately 95 million hectares. Over 8,000 potential hydroelectric opportunities were identified. The Consulting Engineers of British Columbia recognized RHAM with an Award of Merit in 2008. RHAM is being applied in other parts of the world to unlock hydroelectric potential, reduce carbon fuel dependence, and help ensure a sustainable energy future for the world.

With the recent and continuing increases in energy consumption, combined with strong environmental concerns, there has been a resurgence in the development of low-impact hydroelectric projects throughout North America and internationally. Within North America, the proposed developments have generally been limited to smaller run-of-river developments or the addition of low-head powerplants to existing in-river structures. Of particular interest have been the hydropower additions adjacent to existing lock and dam structures within the Ohio and Upper Mississippi River Basins. The existing lock and dam facilities are maintained and operated by the U.S. Army Corps of Engineers and were developed to provide safe and efficient navigation along the rivers for commercial transport of goods. With the addition of a hydropower project, the developer is required to demonstrate that there will be no adverse impacts on navigation and flood levels within the vicinity of the project.

This paper will consolidate and discuss the results of nine physical model studies that have been conducted for hydropower additions adjacent to existing lock and dam projects. The primary objective for each of the studies was to evaluate and resolve any impacts on navigation that the proposed development might impose. Secondary objectives have included verifying that the project would not adversely impact flood levels, scour and erosion or environmental habitats in the vicinity of the project. In addition, the project designers have utilized the models to refine the alignment and geometry of the powerhouse approach channel to minimize head losses while providing uniform flow distribution entering the powerhouse intake. In each case, the physical modeling was instrumental in optimizing a project layout that minimized the impacts on river navigation while providing approach and tailrace flow conditions compatible with efficient power generation. The experience gained and the “lessons learned” on the various projects are summarized and discussed, and design recommendations are developed that can be applied to future projects

A simulation model was created to identify dam operations and configurations that provided high survivals for Juvenile salmonids migrating out of the Snake River. Regional fisheries managers sought to identify ways to operate and configure the dams and the fish transportation system (barging) to provide safe passage conditions and survival rates that met or exceeded criteria set forth in the Biological Opinion. The challenge was to determine whether a candidate operation or construction item provided the expected survival benefits when the operations and configurations of the entire system were considered. The expected influence of candidate operations and configurations was simulated to screen many millions of combinations and identify the subset that met minimum criteria. Acceptable combinations exhibited a range of survival values, construction costs, and power revenues. This approach provided a set of cost effective combinations from which a mix of survival benefits, construction costs, and power revenues could be chosen to meet stewardship goals.

Both ground rain gauge and remotely sensed precipitation (Next Generation Weather Radar - NEXRAD Stage III) data have been used to support spatially distributed hydrological modeling. This study is unique in that it utilizes and compares the performance of National Weather Service (NWS) rain gauge, NEXRADStage III, and Tropical Rainfall Measurement Mission (TRMM) 3B42 (Version 6) data for the hydrological modeling of the Middle Nueces River Watershed in South Texas and Middle Rio Grande Watershed in South Texas and northern Mexico. The hydrologic model chosen for this study is the Soil and Water Assessment Tool(SWAT), which is a comprehensive, physical-based tool that models watershed hydrology and water quality within stream reaches. Minor adjustments to selected model parameters were applied to make parameter values more realistic based on results from previous studies. In both watersheds, NEXRAD Stage III data yields results with low mass balance error between simulated and actual streamflow (±13%) and high monthly Nash-Sutcliffe efficiency coefficients (NS > 0.60) for both calibration (July 1, 2003 to December 31, 2006) and validation(2007) periods. In the Middle Rio Grande Watershed NEXRAD Stage III data also yield robust daily results(time averaged over a three-day period) with NS values of (0.60-0.88). TRMM 3B42 data generate simulations for the Middle Rio Grande Watershed of variable quality (MBE = +13 to )16%; NS = 0.38-0.94; RMSE = 0.07-0.65), but greatly overestimates streamflow during the calibration period in the Middle Nueces Watershed.During the calibration period use of NWS rain gauge data does not generate acceptable simulations in both watersheds. Significantly, our study is the first to successfully demonstrate the utility of satellite-estimated precipitation (TRMM 3B42) in supporting hydrologic modeling with SWAT; thereby, potentially extending therealm (between 50 degree North and 50 degrees South) where remotely sensed precipitation data can support hydrologic modeling outside of regions that have modern, ground-based radar networks (i.e., much of the third world).